The purpose of the work described in this application is to archive data from the Study of Dementia in Swedish Twins, funded by NIH Grant No. R01 AG08724, with the Inter-University Consortium for Political and Social Research (ICPSR) at the University of Michigan. Included in the archive will be data from fourteen years of funding by R01 AG08724 for all twins who were members of the Swedish Adoption/Twin Study of Aging (SATSA) population. These data will complement data already archived with ICPSR from SATSA. The proposed Dementia in Swedish Twins data archive will comprise results of cognitive screening that took place at multiple times, results of diagnostic evaluations for dementia for twins who showed evidence of cognitive impairment and for their twin siblings, scores on cognitive tests included in the dementia evaluation, longitudinal cognitive test scores for twin pairs in which one or both was demented, medical history and medical risk factors, and lifestyle and behavioral risk factors. In all, 1075 individuals in the SATSA population, including 330 complete pairs, participated in one or more of the assessments funded by the Study of Dementia in Swedish Twins. Cognitive screening results are available for 881 individuals. Over the course of the study, 368 individuals both probands and twin siblings were assigned consensus clinical diagnoses; of these, 185 were diagnosed as demented. Archiving entails converting the complex survey and clinical data into controlled access public use files with user-friendly formats that facilitate data use. The activities described in this application include formatting datasets and creating documentation consistent with ICPSR standards. Direct identifiers are already removed; in the course of preparing data files for archiving, we will further deidentify the data to protect the confidentiality of participants. Data archiving serves the purpose of enabling other investigators to make use of this resource, both by itself, and through pooling data across different studies with similar information. PUBLIC HEALTH RELEVANCE: Data archiving is encouraged by NIH as a way to make data as widely and freely available as possible to the research community while safeguarding the confidentiality of participants. Those participating in the original studies were motivated to contribute to knowledge about sources of cognitive decline in older adults. Archiving serves the aspirations of those participants and the interests of public health by permitting the fullest possible use of the information that was collected. The research question that can be addressed by those using the data archive is of intense public interest, namely, discovering potentially modifiable lifestyle factors and health behaviors that improve the probability for maintaining cognitive health in old age. [unreadable] [unreadable] [unreadable] [unreadable]